Long life to olive oil and wine! Long life with olive oil and wine?

Abstract

It is well known that among European countries, those in the Mediterranean area, including Italy, France, Spain, and Portugal show a lower mortality for cardiovascular diseases compared to those in Northern Europe and even more to those in Eastern European countries [1]. The most likely explanation for this phenomenon is related to the Mediterranean diet. Indeed, the Scientific Advisory Committee of the American Heart Association underscores the importance of a Mediterranean-style diet to obtain a beneficial effect on the onset and progression of cardiovascular disease [2]. Recently, this diet was demonstrated to be associated with an improvement in endothelial function and a reduction of markers of systemic vascular inflammation in high-risk patients [3]. Traditional Mediterranean diet is rich in vegetables, fruits, cereals, and legumes, with relative low meat consumption. Calories from fat are 25–35% and saturated fats are only 7–8% of total calories. The main source of fat is represented by olive oil, which has been demonstrated to have antiatherosclerotic properties. These are partly related to its content in cholesterol-lowering monounsaturated fatty acids, and partly to the nonsaponifiable fraction (0.5–1%), containing vitamins such as α- and γ-tocopherols, β-carotene, phytosterols, pigments, terpenic acids, flavonoids (e.g. luteolin and quercetin), squalene and other phenolic compounds [4]. The most abundant olive oil phenols are the secoiridoid oleuropein, hydroxytyrosol (3,4-dihydroxyphenylethanol), and tyrosol. These cathecholic compounds show a potent antioxidant activity [4]. Another fundamental component of the Mediterranean diet is represented by wine. Ethanol, in general, has a whole range of cardiovascular protective effects when consumed in low to moderate doses, with favorable changes in lipid metabolism, insulin sensitization, antioxidant effects, inhibition of platelet aggregation, improvement in endothelial function, and anti-iflammatory property [5]. Besides ethanol, wine appears to be more cardioprotective than beer, and in particular, red wine has components such as polyphenols and quercetin, with putative additional beneficial effects over white wine [6,7]. In the present issue of the Journal of Hypertension, Papamichael et al.[8] report the results of a study evaluating the combined postprandial effects of wine and olive oil on wave reflections and central hemodynamics. Fifteen healthy subjects consumed, on different days, four standard meals containing 50 g of olive oil and 250 ml of wine, in a randomized cross-over study design. The authors used the four possible combinations with two types of wine (red and white) and two types of olive oil (green and refined), rich and poor in antioxidants, respectively. Arterial stiffness was evaluated by applanation tonometry and aortic pulse wave analysis under basal conditions and 1, 2 and 3 h postprandially, calculating aortic blood pressures, and augmentation index (AIx). Firstly, all combinations were able to decrease AIx compared with control group. Moreover, the combinations containing red wine were characterized by a more prolonged effect compared with those with white wine. Finally, all combinations induced a significant decrease in central blood pressure values. The authors conclude that combined consumption of wine and olive oil provides beneficial effects on postprandial hemodynamics. The present study might have important clinical implications. Firstly, postprandial state, mainly after a high-calorie meal, is characterized by a rise in blood glucose, triglycerides and free fatty acids [9]. As a consequence, the overload with caloric substrates overwhelms the Krebs cycle inside adipocytes, and muscle cells and the cellular levels of NADH reach a level that cannot be processed through the oxidative phosphorylation. The increase in mitochondrial proton gradient that follows drives the transfer of single electrons to oxygen, producing superoxide anions and other radicals [9]. Eventually, the postprandial state is a high oxidative stress state that triggers various proatherosclerotic mechanisms, including endothelial dysfunction, vascular inflammation, sympathetic activity, thrombogenicity, and oxidation of LDL [9]. As reported by Papamichael et al.[8], an increase in arterial stiffness might also follow a standard meal, probably in relation to the mentioned mechanisms. Although theoretically transitory in relation to the postprandial state, these phenomena are conceivably greatly relevant in human atherothrombosis when repeated multiple times during the day, and it is calculated that Americans spend most of their waking time in postprandial state [9]. Therefore, the implementing of strategies to reduce the postprandial dysmetabolism might confer a potential protection on the cardiovascular system. The result of the study by Papamichael et al.[8] together with data present in the literature suggests that some of the components of the Mediterranean diet might ‘naturally’ protect through their antioxidant activity as well as other still unknown mechanisms. Secondly, the authors did not find astounding differences among the study intervention regimens. Although evidences are not strong yet, red wine is usually considered more cardioprotective than white wine. Indeed, in human studies de-alcoholized red but not white wine possesses cardiovascular benefits [6], likely related to the presence of polyphenols, such as resveratrol in red wine. The study by Papamichael et al.[8] was able only to demonstrate a longer duration of the protection against AIx increase in the two study groups assigned to red wine as compared to those assigned to white wine. It is, however, worthy of note that AIx and arterial stiffness are integrated indexes of complex mechanisms affecting the large arteries structure and function [10]. Therefore, it is not surprising that the benefit obtained with red wine on these parameters is only modest, considering that only the acute effect was investigated. It is likely that a study design with a prolonged treatment period and longer follow-up might unveil additional benefit achievable with various combinations of different types of wine and oils also on parameters of large arteries function such as AIx. Another important issue concerns the putative underestimation of the effect of the used dietary regimens in a healthy population such as that studied by Papamichael et al.[8]. It is conceivable that in higher risk populations a stronger discriminative power would allow detection of differences among the groups. In conclusion, the paper by Papamichael strengthens the hypothesis that the combination of two main components of the Mediterranean diet, olive oil and wine, can be a valid tool to prevent vascular damage, and in particular, arterial stiffening, apparently in part independently from the type of the nutrient (red versus white wine, green versus refined oil). Whether the combination of oil and wine is superior to each of the two, however, cannot be derived from the study. Finally, the long-term significance of this finding is not known and should be further investigated.